That is because Bandera was a straight up Nazi collaborator who took part in Pogroms, killing a LOT of Jewish Ukrainians.

I find it interesting that this fact is listed on his German Wikipedia page, but is not listed (or has been removed) from his English Wikipedia page.

Bandera was supporting the Nazis in WWII, but they suspected he was 100% not on Germany's side. They suspected (I think correctly) that Bandera shared the Nazi ideology of Antisemitism, but that Bandera would want a parallel Ukrainian state not 100% under the Nazi's rule. That is why the Nazis arrested Bandera.

The Nazis understood Bandera was mostly on their side and could be useful, which is why he was not killed or sent to a concentration camp, and why he was eventually released.

Yes, Bandera was against the Soviet occupiers of Ukraine. He was also a Nazi who committed heinous war crimes including killing a LOT of Jews. That is why "he divides people."